I just read the article "Is Quantum Mechanics necessary for understanding Magnetic Resonance?" by Lars G. Hanson. In its abstract it says "Magnetic resonance is often presented as a phenomenon that necessitates a quantum mechanical explanation whereas it really is a classical effect, i.e. a consequence of the common sense expressed in classical mechanics."
Are there fields in MRI research that require quantum mechanics, or is most research in MRI done using classical mechanics? The article mentions that only if the observed sizes of relaxation rates are calculated based on quantum mechanics do they match experiment. Are there also other fields of MRI research that require quantum mechanics?